1. Field of the Invention
The present invention relates to an image forming apparatus, such as a copying machine and a laser beam printer (LBP), and, more particularly, to a spectral colorimetric apparatus that detects a light beam dispersed using a reflection type diffraction element, using a plurality of photoelectric conversion elements arranged in an array, so as to perform color discrimination or colorimetry on a subject.
2. Description of the Related Art
Sometimes, image forming apparatuses, for forming a color image, cause tint deviation in a color image. Particularly, in an electro-photographic system, due to change in usage environment and deterioration with age, transfer efficiency varies with colors, depending upon drum sensitivity, the charge capacity of the toner used, and the type of paper used. Thus, the color mixing ratio can deviate from a predetermined value which is likely to affect tint of the printed image.
Such a phenomenon occurs, so that tint may be changed due to difference among image forming apparatuses. Accordingly, there is a fear that consistency of the tint of a formed color image cannot be maintained. To solve such an issue, conditions for forming an image by an image forming apparatus are controlled by measuring the tint of a surface using a colorimetric apparatus. Thus, the consistency of the tint of a formed color image is maintained.
Japanese Patent Application No. 2009-110884 (i.e., Japanese Patent Application Laid-Open No. 2010-276599 discusses a colorimetric apparatus of the following configuration. The colorimetric apparatus is a spectral colorimetric apparatus that includes an illumination optical system for illuminating a test surface, a light guide optical system for guiding to a dispersing optical system a light beam reflected from the test surface, and the dispersing optical system for acquiring a spectral intensity distribution by dispersing the guided light beam.
To more accurately measure the tint of the test surface with such a spectral colorimetric apparatus, it is necessary to position the spectral colorimetric apparatus with a high degree of accuracy, with respect to the light beam reflected from the test surface, by adjusting the position and orientation of an optical member. In addition, it is necessary that: the smaller the spectral colorimetric apparatus is, the higher the accuracy of the adjustment of the position and orientation of the optical member becomes.
For example, if the illumination optical system, the light guide optical system, and the dispersing optical system are contained in one housing in order to miniaturize the apparatus, a space, into which tools are inserted for electrically connecting the systems and for multi-axial adjustment thereof, is narrowly limited so as not to touch other optical members. Accordingly, such operations are difficult to perform, and there is a fear of reduction in the productivity of the apparatus.